Saturday, November 28, 2020

A wet Sunday leads to a December chill as cold Canadian air plunges south

With Thanksgiving in the rearview mirror, the 2020 calendar is about to flip one more page to December... and it can't come soon enough! However, if the weather for the month ahead is anything like the first week of December promises to be, I might have to reconsider.

Weekend weather (enjoy today!)

Today might be the last "decent" day in the 7-day forecast period, depending on how you define decent. While we'll have a handful of pretty-to-look-out-the-window-at days, the the cold air shifting our way is no joke for early December. Expect plenty of sunshine for your Saturday with highs in the mid to perhaps upper 50s with a northeast breeze. It'll be a good day to make sure your plants and pets are ready for the arrival of Canadian air on the horizon, as Sunday will be cold and wet. Dry weather continues overnight, but by lunchtime Sunday, rain will be arriving and continue into the evening hours as surface low pressure moves by to our south. The rain and cloud cover will result in temperatures in the 40s throughout the day. A cold north wind will mean heavier raincoats or layers will be the best option if you plan to get out.

The high-resolution NAM3 model forecast precipitation from 6am Sunday to 6am Monday shows the likely progression of rainfall across the Mid-South.

Sunday night flakes?

Sunday evening into Monday morning has been an interesting forecast this week. While surface temperatures stay above freezing (but in the 30s), temperatures in the lowest few thousand feet of the atmosphere are likely to fall below freezing by evening as a cold pocket under an upper level low moves overhead. If it gets cold enough, and precipitation lingers, light rain could mix with a few wet snowflakes with surface temperatures in the mid to upper 30s. These would be "no-worry flurries" that would splat and melt on the ground, and are more likely across parts of west TN northeast of the metro. 

The profile of the atmosphere for Sunday night at midnight shows warm surface temperatures (comparably) but cold (at or below freezing) temperatures between about 3,000-8,000 feet. The big question is whether any frozen precipitation aloft melts before it gets to the ground. (Pivotal Weather)

For now, the chances appear very low in the metro proper, but don't be shocked if you see some. Finally, as the low departs a couple models-in-the-minority want to squeeze out a few snowflakes Monday morning. Doubtful, but not impossible. With temperatures at or above freezing all night, no issues are expected for Monday morning's commute either way. (I see you, teachers heading back to class Monday morning...and I understand.)

The blob of cold air aloft moves over the area Monday and likely keeps some cloud cover around for a good part of the day with clearing sometime in the afternoon or maybe evening. With cold air advection (or, movement of air) continuing, we'll spend most of Monday in the 30s (you read that right) and a northwest wind gusting to 25 mph. Just brutal. Stay in if you can. 

Wind chill forecast for noon Monday according to the NAM3 model. That says "21" for Memphis! (Pivotal Weather)

Early December chill

As the clouds clear and wind dies down Monday night, we're in for the coldest night since before the pandemic (late February to be precise) with temperatures falling into the mid to upper 20s by early Tuesday morning. (See below for a little "Weather 201" on that cold airmass.) That will make it hard to warm a lot on Tuesday, with sunshine only pushing the high temps into the mid 40s. Another hard freeze Wednesday morning (upper 20s) before temperatures get closer to normal again on Wednesday with highs in the lower 50s and dry weather.

This plot is called a "backwards trajectory" and shows where air originated and where it ends up at a certain place/time. In this case, the low-level air over central Canada this (Saturday) morning will move south and be over Memphis Tuesday morning when our temperatures are in the 20s! Where the airmass originates can tell us a lot about the character of that air, even though it will be modified somewhat by the time it gets here. (NOAA/ARL)

Unsettled late week

The next series of atmospheric disturbances move through Thursday into the first weekend of December. The first of these appears weak and models are having issues latching on to how the end of the week and weekend play out. However, rain chances are back in the forecast Thursday, maybe Friday and maybe Saturday. Temperatures will continue to be cold with lows in the mid 30s and highs in the upper 40s. It's way too early to determine if any more s**w chances will be needed, but we'll keep an eye on things and report more when able. 

In a nutshell, December starts out very cold, which means you need to move any sensitive outdoor plants inside, probably winterize the outdoor faucets in the next 24 hours, and make sure that outdoor pets have a place to stay warm and plenty of food and water (not ice). The cool-ish trend looks like it might continue into the second week of December as well!

The week two temperature outlook from the Climate Prediction Center indicates a chance that cooler than average weather continues from December 5-11. (NWS)

Stay warm and well, friends!

Erik Proseus
MWN Meteorologist

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Friday, November 20, 2020

November warmth continues this weekend, but how does Thanksgiving look?

Gorgeous fall weather has been with us much of this week as temperatures have been above average for a few days with dry conditions since Sunday morning's frontal system and brief downpours. As we look towards Thanksgiving and the remaining days of November, can we expect the unseasonably warm weather to continue? And what about rain chances for the holiday?

This weekend

Out next frontal system is still about 48 hours away, but clouds will begin to move in ahead of it tonight into Saturday, shielding the sunshine we've enjoyed this week. However, warmer and moister air will continue to filter in on a southerly breeze, so expect mild overnight conditions tonight with lows in the 50s and warm weather for Saturday with highs near 70 once again. If you are one of the lucky ones with tickets to the Tigers football game Saturday afternoon, here's your Senior Day forecast:

By Sunday, the front moves through and rain chances increase. We'll see scattered showers during the day. Models are still honing in on most likely timing, but it appears best rain chances may be in the morning to early afternoon hours. By late afternoon and evening, we should be dry, but a north wind will make for good weather for the fire pit! After morning lows in the mid 50s, we'll top out in the low 60s before temperatures fall in the afternoon. Rain chances are in the 50-60% range but could climb a bit more as we draw closer. No major deluges are expected with totals in the quarter-inch range.

An early look at what radar might look like from Saturday night at midnight through 6pm Sunday, based on the NAM3 model. Scattered showers are the most likely form of precipitation, ending by mid afternoon. (WxBell)

Early Thanksgiving week

Once the front clears out Sunday evening, we'll be looking at a mix of sun and clouds to start next week with much cooler air in place. Morning lows Monday will be in the lower 40s and highs only in the mid 50s, a bit below average for this time of year. Tuesday will see a return of some warmer air as the weather pattern becomes more progressive and the next system moves our way Tuesday night. Mostly dry though during the daytime hours Tuesday with highs back into the 60s.  Rain appears likely from a more potent and wetter system Tuesday night into Wednesday. A few thunderstorms are even possible and rainfall will be heavier at times than Sunday, but it should move out by the back half of Wednesday. Temperatures will be similar to Tuesday.

An early look at mid-week precipitation totals from the European model. An inch or more is possible in the Memphis metro. (WxBell)

Thanksgiving forecast

If you are hoping (and planning) to spend time outdoors for Thanksgiving, conditions at this time appear to be fairly good with slightly above average temperatures continuing for Turkey Day and into the following weekend (mid 60s for afternoon highs, upper 40s for early morning lows). Dry weather looks to be on tap with the next frontal system not expected until at least Friday and possibly Saturday. I think it is safe to make your plans accordingly, but keep an eye on the MWN Forecast and our social media feeds (linked below) in case the mid-week system slows down or the late week front speeds up!

Erik Proseus
MWN Meteorologist

Follow MWN on Facebook and Twitter for routine updates and the latest info!
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Saturday, November 7, 2020

A pleasant weekend, then cooler with possible rain chances next week

Weekend weather

Above normal temperatures will continue over the weekend with highs in the mid to upper 70's, which is roughly 10 degrees above normal.  Lows will be in the low 60's, which is about 15 degrees above normal.  The reason behind all these warm temperatures is the ridge of high pressure that is to our northeast over Virginia, which is allowing warm southerly/southeasterly winds to spread over the area.  This setup will continue into the start of the work week.  It will be a warm with a good deal of sunshine, perfect for going outside, even as we move deeper into November.

Mid-week cold front

By Tuesday afternoon, a cold front that is currently over the wester U.S. will begin to move thru the area, with scattered rain chances as it moves through.  This front will be moving into an area of rather strong high pressure, and this has a tendency to suppress precipitation.  The best chances of rain appear to be Tuesday night and even then only 30-40%. Behind this front on Wednesday, we'll see cooler temperatures, but still highs in the upper 60's and lows in the lower 50's, which is near normal.  

The surface map for early Saturday morning shows a front in the western U.S. that will move through the Mid-South Tuesday night. (NWS)

Temperatures would normally be much cooler behind a November front, but because this one originates in the Pacific and not Canada, the airmass behind it is not as chilly. In addition to the slightly cooler temperatures, we'll also see a return of northerly winds.  These near-average temperatures will continue through the end of the week.

Next weekend - colder air?

Additional precipitation chances will increase towards next weekend with another cold front that is currently near Alaska.  Timing right now is a bit different between models, but the timing of this should become more accurate after the front moves onshore Monday in western Canada.

One other thing we are watching is Tropical Depression Eta, which is currently in the central Caribbean Sea headed towards the Cayman Islands.  Eta will move northeast over Cuba this weekend, into the Florida Straits on Monday, then into the eastern Gulf of Mexico Tuesday.  Eta looks to remain a tropical storm, but should make landfall sometime late next week, likely around the Florida panhandle.  The current track of this storm keeps any rainfall well east of our area, but any shift to the west could bring us some rain next weekend.  We will continue to watch the progress of Eta and update the forecast accordingly.

The National Hurricane Center's forecast track for Eta as of Saturday morning.(NOAA/NHC)

Get out there this weekend and enjoy the sunshine, warm temps and dry weather!  It may be the last one of the year!

Richard Hoseney
MWN Meteorologist

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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder

Friday, November 6, 2020

October 2020 Climate Data for Memphis, TN

October Climate Recap

October is a month that Memphis typically starts seeing cold fronts move through as summer months move into the rearview mirror. Temperature swings multiple times over this month indicate that happened, with repetitive warm spells followed by cool spells. Overall, the monthly average ended up a bit over a degree below normal with a large gap between the warmest temperature (85) and the coolest temperature (39). There were no frost or freeze days anywhere in the metro during the month despite upper 30s to end the month.

This month, a good deal of rain fell, resulting in about 3/4" of rain above normal. However, a great deal of that total (about 93%) fell on just 2 days - both due to tropical remnants. Between those two events, a run of 17 days produced only 0.04". The first rainy day occurred on the 10th as the remnants of former Hurricane Delta moved through north MS. The wettest day of the month was the 28th when 2.68" fell at the airport.  This was the result of former Hurricane Zeta moving into MS and AL, but it's moisture combining with a stalled front to drop 2-3" across the region. Both systems made landfall in Louisiana and curved northeast to the south of Memphis. The only weather alerts issued in the Memphis metro in October were a pair of Flood Advisories as rain became heavy on the 28th.

Memphis International Airport, Memphis, TN

Average temperature: 62.8 degrees (1.3 degrees below average) 
Average high temperature: 72.3 degrees (2.1 degrees below average) 
Average low temperature: 53.3 degrees (0.5 degrees below average) 
Warmest temperature: 85 degrees (20th, 21st, 22nd) 
Coolest temperature: 39 degrees (30th) 
Heating Degrees Days: 132 (12 above average)
Cooling Degree Days: 72 (20 below average) 
Records set or tied: None 
Comments: None

Monthly total: 4.69" (0.71" above average) 
Days with measurable precipitation: 6 (1.5 days below average) 
Wettest 24-hour period: 2.68" (28th) 
Snowfall: None 
Records set or tied: Record daily rainfall - 2.68 " (28th)
Comments: Ninety-three percent of October's rainfall was due to the remnants of two tropical systems.

Peak wind: East/34 mph (10th) 
Average wind: 7.0 mph 
Average relative humidity: 70% 
Average sky cover: 50% 

 Click here for a daily statistical recap for Memphis International Airport.

Cirrus Weather Solutions /, Bartlett, TN

Average temperature: 60.3 degrees 
Average high temperature: 71.8 degrees 
Average low temperature: 50.6 degrees 
Warmest temperature: 85.3 degrees (21st) 
Coolest temperature: 37.8 degrees (31st) 
Comments: None 

Monthly total: 4.81" (automated rain gauge), 5.00"(manual CoCoRaHS rain gauge) 
Days with measurable precipitation: 9
Wettest date: 2.31" (10th) (via automated gauge) 
Snowfall: None 
Comments: None 

Peak wind: Northeast/22 mph (10th)
Average relative humidity: 82% 
Average barometric pressure: 30.05 in. Hg
Comments: None

Click here for a daily statistical recap for Bartlett, TN.

MWN Forecast Accuracy

MWN average temperature error: 2.21 degrees 
MWN forecast temperatures within 2 degrees of actual: 68% 
MWN average dewpoint error: 2.07 degrees 
MWN forecast dewpoints within 2 degrees of actual: 70% 

MWN's forecasts extend out five periods (2.5 days, or roughly 60 hours). Historical accuracy statistics can be found here.

Climate Outlook - November 2020

The November climate outlook for the United States from the Climate Prediction Center is shown below. Above average temperatures are forecast for much of the United States, with highest probabilities in the Northeast U.S. and Southern Plains west through the Desert Southwest. Odds favor above average temperatures for Memphis (a 38% chance), where the average temperature for November is 53.2 degrees.

Precipitation is expected to be below normal across much of the southern U.S. in November, particularly in the Southern Plains with slightly above average precipitation in the Pacific Northwest. For Memphis, odds favor below average rainfall (a 46% chance) versus only an 21% chance of above average rainfall. Precipitation historically averages 5.49 inches in November. 

Follow MWN on Facebook and Twitter for routine updates and the latest info! 
Complete MWN Forecast: on the mobile web or via the MWN mobile app 
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MWN is a NOAA Weather Ready Nation Ambassador Meteorologist Erik Proseus is an NWA Digital Seal Holder